blue Kutani 8.5" plates

they are a beautiful blue, crazed from age no chips, in mint condition.  I have 2 sets 6 in total but 3 have one stamp and 3 have the other.  I recieved these as a gift from a friends mother who purchased these in the 40 and I found a price tag for one set of 45.00.  I have looked at several sites online and had someone local look at them and he could not find them either.  Thank you for you help I dont want to sell them until I know what they are worth.